DE102015107248B4 - Adjustable vibration damper - Google Patents

Abstract

Controllable vibration damper (1), in particular for a motor vehicle chassis, comprising a cylinder tube (10) having a hydraulic fluid received therein sealed, a piston (2) which is axially movable within the cylinder tube (10) along a cylinder tube axis (A) and the cylinder tube (10) divided into two working spaces (11, 21), a piston rod (3) which is aligned parallel to the cylinder tube axis (A) and connected to the piston (2), wherein the piston (2) at least two fluid passages (12 , 22), by which the one working chamber (11, 21) is connected to the other working space (21, 11), wherein a first valve assembly (13) for damping the piston movement in a first actuating direction (R1) on a first fluid passage ( 12) is arranged and wherein a second valve assembly (23) for damping the piston movement in a second actuating direction (R2) on a second fluid passage (22) is arranged, each V valve assembly (13, 23) has at least one valve disc (14, 24) which is seated in a closed valve position on a valve seat (15, 25) and which is at least partially spaced from the valve seat (15, 25) in an open valve position, wherein each valve assembly (13, 23) comprises a pilot chamber (16, 26), wherein by pressurizing the pilot chamber (16, 26) the valve disc (14, 24) is biased into the closed valve position, the pressure in the respective pilot chambers (16 , 26) is adjustable by at least one pilot valve (31), wherein the pilot valve (31) comprises a valve body (32) which is movable in a defined manner between a closed position and an open position, whereby a flow cross-section between the pilot chambers (16, 26) and the working spaces (21, 11) is specifically adjustable,
wherein a first discharge path (18) and a second discharge path (19) adjoin the valve body (32) on the outlet side, wherein the first discharge path (18) is closed when an actuator (40) for controlling the position of the valve body (32) is inactive .
characterized,
in that a closing element (37) designed separately from the valve body (32) is provided for closing the first drainage path (18).

Description

The present invention relates to a controllable vibration damper, in particular for a motor vehicle chassis.

STATE OF THE ART

The WO 2010 122 102 A1 shows a controllable vibration damper, in particular for a motor vehicle undercarriage, comprising a cylinder tube having a hydraulic fluid contained therein sealed, a piston which is axially movable within the cylinder tube along a Zylinderrohrachse and divides the cylinder tube into two working spaces, a piston rod which is parallel to Cylinder tube axis aligned and connected to the piston, wherein the piston has at least two fluid passages through which the one working space is connected to the other working space, wherein a first valve assembly for damping the piston movement in a first actuating direction to a first fluid passage is arranged and wherein second valve assembly for damping the piston movement in a second actuating direction is arranged on a second fluid passage, wherein each valve assembly has at least one valve disc, which in a closed valve position a uf seated on a valve seat, and which is at least partially spaced from the valve seat in an open valve position, wherein each valve assembly comprises a pilot chamber, wherein by pressurizing the pilot chamber, the valve disc is biased into the closed valve position.

The DE 10 2013 114 169 A1 discloses variable vibration damper, in particular for a vehicle chassis, comprising a cylinder tube having a hydraulic fluid sealed therein, a piston which is axially movable within the cylinder tube along a Zylinderrohrachse and divides the cylinder tube into two working spaces, a piston rod, which is aligned parallel to the cylinder tube axis is and is connected at one end to the piston, wherein in the piston a plurality of fluid passages are provided from a working space in the other working space, wherein a first valve assembly for damping the piston movement in a first actuating direction in a first fluid passage is arranged and wherein a second valve assembly for Damping of the piston movement is arranged in a second actuating direction in a second fluid passage, wherein each valve assembly has at least one valve disc which seated in a closed valve position on a valve seat t and which is at least partially remote from the valve seat in an open valve position, each valve assembly comprising a pilot chamber, a pressure in the pilot chamber biasing the valve disc into the closed valve position, the pressure in the respective pilot chambers being adjustable.

In principle, it is preferred in such vibration dampers, if the damping characteristic of the vibration damper in the individual stages (pressure level, movement of the piston in the direction of the piston rod remote working space or rebound, movement of the piston in the direction of the piston rod side working space) are set as independent as possible from the respective other stage can.

A special possibility of such individual adjustability is in the DE 10 2011 000 566 B3 A shrinkage damper with controllable pilot control is described here, in which the active surfaces on the pilot control valve are designed differently for both stages. Thus, a different loading of the valve body is generated during the individual stages. However, so far can not apply to such valve body, with which the switching between two drainage paths should be realized. Because in the pressure stage of the valve body is acted upon directly by the working pressure in the piston rod remote working space. From a certain piston speed, the valve body is fully opened and transferred to its upper stop position. If, however, the valve body at the same time should also take over the switchover to the failsafe function, the stop position at the same time also blocks the regular (first) discharge path and activates the (second) discharge path via the failsafe valve.

DISCLOSURE OF THE INVENTION

Based on this, it is the object of the present invention to develop an improved controllable vibration damper, and in particular to provide an improved and universally applicable option for adjusting the damping characteristic individually for the individual stages.

The object underlying the invention is achieved by a controllable vibration damper according to claim 1; preferred embodiments will become apparent from the dependent claims and the following description.

Thus, according to the invention, a controllable vibration damper, in particular for a motor vehicle chassis, is proposed. Such a vibration damper comprises a cylinder tube having a hydraulic fluid received therein sealed, a piston axially within the cylinder tube along a cylinder tube axis is movable and divides the cylinder tube into two working spaces, a piston rod which is aligned parallel to the cylinder tube axis and is connected at one end to the piston. In the piston, at least two fluid passages are provided, through which one working space is connected to the other working space, wherein a first valve assembly for damping the piston movement in a first actuating direction on a first fluid passage is arranged and wherein a second valve assembly for damping the piston movement in a second Operating direction is arranged on a second fluid passage, each valve assembly having at least one valve disc which is seated in a closed valve position on a valve seat, and which is at least partially spaced from the valve seat in an open valve position. Each valve assembly comprises a pilot chamber, wherein by pressurizing the pilot chamber, the respective valve disc is biased into the closed valve position, wherein the pressure in the respective pilot chambers by at least one, in particular exactly one, pilot valve is adjustable, wherein the pilot valve comprises a valve body defined between a closed position and an open position is movable, whereby a flow area between the pilot chambers and the work spaces is selectively adjustable.

The valve body is followed by a first drain path and a second drain path on the outlet side, wherein the first drain path is closed when an actuator for controlling the position of the valve body is inactive. The first drain path is then closed by the valve body in a failsafe state (e.g., power supply failure of the actuator). The fluid is then largely forced to drain through the second drain path. In this second flow path can then be arranged a failsafe valve with which a targeted pilot pressure can be established, in the event that pilot valve is inoperative.

The vibration damper according to the invention is characterized in that a closure element designed separately from the valve body is provided for closing the first drainage path.

By this arrangement, a separation of functions between the setting of the pilot pressure on the one hand and the switching between the two flow paths on the other hand is realized first. This makes it possible for certain applications in the first place possible to select and control different drain paths regardless of the position of the pilot valve for the flow of fluid from the pilot valve.

The invention is particularly applicable to such a vibration damper, the valve body are associated with at least two active surfaces. If these active surfaces are pressurized by fluid during operation, they in turn act upon the valve body in its open valve position. The active surfaces may be attached to the valve body itself; but they can also be arranged on separate components which are in corresponding interaction with the valve body. The sum of the active areas pressurized during the piston movement in one of the two actuating directions, in particular the second actuating direction, is less than the sum of the effective areas pressurized during the piston movement in the other of the two actuating directions, in particular the first actuating direction.

In other words, during one stage, the pilot pressure acts only on a smaller effective area in total, while the other stage, the pilot pressure acts on a larger total area. This acts directly on the forces with which the valve body is acted upon in its open position.

In particular, the invention is applicable when the valve body is acted upon in one of the two stages, in particular the pressure stage, directly by the working pressure in the respective pressurized, in particular the piston rod remote, working space.

Due to the increased loading of the valve body in one of the stages, the valve body can easily get into its open stop position, which blocks the first discharge path, without the need to close this due to a malfunction. Due to the above-mentioned separation of functions, the first drain path can remain open even when the valve body in its open position is in abutment, since taking this position no longer automatically causes the switching between the two drainage paths.

Furthermore, the invention is particularly applicable to such vibration dampers, which comprises exactly one valve body for adjusting the pilot pressure in both pilot chambers and whose position is adjusted by means of an actuator during operation targeted.

The closing element is in particular selectively displaceable between a closed position in which it closes an inlet opening of the first drainage path and an open position in which it releases the inlet opening. The term closing is not to be understood too narrowly; an absolute tightness of the closure produced is not required.

Preferably, in the case of the inactive actuator, the magnetic closing element can be acted upon by the present in the second flow path pressure in its closed position. This can be achieved, in particular, by means of suitable bores or the like, by means of which the pressure from the second discharge path is directed to the rear side of the magnetic closing element. Any pressure peaks in the area of the pilot valve have the effect of closing rather than opening on the closing element.

Preferably, the closing element is magnetically controlled. The closing element itself may be magnetic or fixedly connected to a magnetic body. The closing element may be disc-shaped.

Preferably, the closing element is arranged in the magnetic flux immediately adjacent to a magnetic element, in particular an armature, which acts on the valve body in its closed position as soon as the magnetic element itself is magnetically acted upon. On a separate magnetic Polrohrabschnitt can be dispensed with, which can result in a component reduction. The closing element may have a sleeve extension which extends in the direction of this magnetic element, so that the magnetic flux can enter the closing element.

Preferably, a common return element, in particular return spring, is provided for returning the valve element and the closing element. This common return element can be arranged between the aforementioned magnetic element and the closing element. In particular, it serves for acting on the valve body in its open position and for acting on the closing element in its closed position, in which it closes the first drain path. This can also result in a component reduction, as can be dispensed with separate return elements for the valve element and the closing element.

Preferably, an actuator for loading the closing element is provided in the open position. This actuator is the same actuator, by means of which the position of the valve body is controlled. If this actuator is able to control the valve body position, it is active. Then, the magnetic flux generated by this actuator can also be used to hold the closure member in its open position. If this actuator is no longer able to control the position valve body, so this is inactive and does not generate magnetic flux; then the closing element is acted upon by suitable return means or the fluid in the closed position.

The invention is particularly applicable to such vibration dampers, wherein in particular in the first flow path or the first discharge path downstream of the valve body drain valve is associated, through which the drain side acting on the valve body back pressure is buildable.

list of figures

• 1 ein Vergleichsbeispiel eines Schwingungsdämpfer im Querschnitt;
• 2 ein erster erfindungsgemäßer Schwingungsdämpfer im Querschnitt in einem ersten Betriebszustand;
• 3 der erste Schwingungsdämpfer nach 2 im Querschnitt in einem zweiten Betriebszustand;
• 4 ein zweiter erfindungsgemäßer Schwingungsdämpfer im Querschnitt in einem ersten Betriebszustand;
• 5 der zweite Schwingungsdämpfer nach 4 im Querschnitt in einem zweiten Betriebszustand.

Further, the invention further developing measures are shown below together with the description of preferred embodiments of the invention with reference to the figures. It shows:

• 1 a comparative example of a vibration damper in cross section;
• 2 a first inventive vibration damper in cross section in a first operating state;
• 3 the first vibration damper after 2 in cross-section in a second operating state;
• 4 a second inventive vibration damper in cross section in a first operating state;
• 5 the second damper after 4 in cross-section in a second operating state.

1 shows as a comparative example an unclaimed vibration damper 1 The vibration damper 1 includes a cylinder tube 10 in which a piston 2 along a cylinder tube axis A is held displaceable. The piston 2 has on its outer circumference a ring seal or a piston band 28 on, leaving the piston 2 the cylinder tube 10 in a first (off-the-rod) workspace 11 and in a second (piston rod side) working space 21 subdivided. The piston 2 is on a mounting pin 42 attached, which in turn firmly with a piston rod 3 connected is. Upon actuation of the piston rod 3 in a first direction of actuation R1 to the first workroom 11 (also called "pressure direction") increases the pressure in the first working space 11 , Fluid, which in the first working space 11 is present, then flows through a first fluid passage 12 in the piston 2 in the second workspace 21 , In this case, the fluid flows through the first fluid passage 12 and by a first valve assembly 13 with a pressure relief valve 14 , The pressure relief valve 14 can eg consist of one or more flexible valve discs 14 be formed. Upon reaching a minimum pressure of the fluid in the first working space 11 becomes the first pressure relief valve 14 which preloaded on a first valve seat 15 seated, from the first valve seat 15 at least partially solved. This is how the valve disc becomes 14 transferred from the closed position in the raised position of the valve seat, open position. A hydraulic connection is made between the first working space 11 and the second workspace 21 produced. The first pressure relief valve generates 14 in interaction with the first valve seat 15 the damping force.

The pressure relief valve 14 is through a in a first pilot chamber 16 prevailing pressure (hereinafter "pilot pressure") in the direction of the valve seat 15 applied. This pilot pressure in the first pilot chamber 16 can be set during operation defined. It can be seen that the opening pressure of the pressure relief valve 14 the higher, the higher the pilot pressure in the first pilot chamber 16 is. The pilot pressure thus influences the characteristic curve of the damping force in the pv diagram. A bypass channel 29 is provided to realize a bypass flow, the valve discs 14 bypasses.

The vibration damper 1 further comprises a second valve assembly 23 , which is designed analogously to the first valve assembly 13 , The second valve assembly 23 is intended to decelerate the flow of the fluid when the piston 2 in a second direction of actuation R2 (also called "pulling direction") is moved. In this case, the fluid flows from the second working space 21 via a second fluid passage 22 in the first workroom 11 , The second valve disc 24 is through a in a second pilot chamber 26 prevailing pilot pressure in the direction of the valve seat 25 applied. The second valve disc 24 and a second valve seat 25 are analogous to the corresponding components of the first valve assembly 13 educated.

The two pilot chambers 16 . 26 are hydraulically connected to each other via a connecting bushing 9 connected. The connection implementation 9 is over a radial bore 44 with an annular chamber 49 connected. The annular chamber 49 opens into a pilot valve chamber 50 a further explained below pilot valve 31 , Essentially, there is the hydraulic connection by means of the connecting bushing 9 in both pilot chambers 16 . 26 always the same pressure. If now the piston 2 in the first direction of actuation R1 is moved, so increases the pressure in the first working space 11 and the damping fluid flows through a fluid passage 27 between the first workspace 11 and the second pilot chamber 26 from the first workroom 11 in the second pilot chamber 26 , whereby the pilot pressure in the second pilot chamber 26 is increased. Through the connection implementation 9 through the planted in the second pilot chamber 26 Built pilot pressure also in the first pilot chamber 16 continued. This will cause the pilot pressure in the first pilot chamber 16 generated with the damping behavior of the first valve assembly 13 being affected. The same applies to the operation in the second direction of actuation R2 , In this case, the fluid flows from the second working space 21 through a fluid passage 17 between the second workspace 21 and the first pilot chamber 16 in the first pilot chamber 16 , The pilot pressure, so in the first pilot chamber 16 is generated, in turn, planted by the connection implementation 9 in the second pilot chamber 26 continued. So that the fluid through the fluid passages 17 . 27 not from the first pilot chamber 16 directly into the second workspace 21 or from the second pilot chamber 26 in the first workroom 11 can flow is in the fluid passages 17 . 27 one-way valve each 20 attached, which are designed for example as check valves.

The pilot pressure in the two pilot chambers 16 and 26 can be regulated. This is the already mentioned pilot valve 31 provided, which a valve body 32 having. The valve body 32 is movable along the cylinder tube axis A held and can be mounted on a fixed (relative to the mounting pin) valve seat 33 seated. When the valve body 32 on the valve seat 33 is seated, is a drain of fluid, which from the pilot chambers 16 . 26 through the annular chamber 49 in the pilot valve chamber 50 flows through the pilot valve 31 largely prevented. Is the valve body 32 from the valve seat 33 solved, so can through the pilot valve 31 Fluid from the connection bushing 9 and the annular chamber 49 flow away. Using the position of the valve body 32 the pilot pressure can be adjusted. The valve body 32 is doing by means of a magnetic actuator 40 on the valve seat 33 to, ie in the first direction of actuation R1 , charged. A feather 30 is intended for recovery and acts on the valve body 32 from the valve seat 33 away, ie in the direction of the second operating direction R2 , Further, the valve body 32 by the pilot pressure from the valve seat 33 acted upon. Depending on the balance of forces caused by the magnetic actuator 40 , the feather 30 and the pilot pressure, then gives the position of the valve body 32 opposite the valve seat 33 ,

The fluid passing through the pilot valve 31 flows out, flows in actuation of the piston rod in the direction R1 (Pressure level, increased pressure in first working space 11 ) through a second drain passage 34 to the second workspace 21 , In the second drainage passage 34 is a one-way valve 36 arranged. The one-way valve 36 prevents in this case, that fluid from the second working space 21 through the pilot valve 31 in the direction of the pilot chambers 16 . 26 can get.

Upon actuation of the piston rod 3 in the direction R2 (Rebound, increased pressure in second working space 21 ) flows through the pilot valve 31 effluent fluid through a first drain passage 38 to the first workroom 11 , The first drainage passage 38 is through an axial hole in the mounting pin 42 educated. A one-way valve 39 in the drainage passage 38 prevents fluid from the second working space 21 through the pilot valve 31 in the direction of the pilot chambers 16 . 26 arrives. In addition, the two prevent one-way valves 36 . 39 a direct connection of the two workrooms 11 . 21 over the drainage passages 34 . 38 ,

For the outflow of between the valve body 32 and the valve seat 33 passing fluid are two possible drainage paths 18 . 19 intended:

For regular operation is a first drain path 18 intended. At the end of this first drainage path 18 can be a drain valve 7 be provided, through which the pressure conditions in the first flow path 18 can be adjusted. In addition to or instead of the throttle shown in the left half of the picture, such a drain valve 7 also have a (possibly connected in parallel) pressure relief valve, which is shown by way of example in the right half (without reference numeral).

In case of a defect of the magnetic actuator 40 eliminates the application of the valve body 32 through this magnetic actuator 40 , The valve body 32 is thus only by the spring 30 and the pilot pressure applied and so shifted upward. Then the valve body blocks 32 an entrance opening 41 the first drainage path 18 , The fluid then flows through a second drain path 19 in which a failsafe valve 8th is arranged. In addition to or instead of the throttle shown in the left half of the picture, such a fail-safe valve 8th also have a (possibly connected in parallel) pressure relief valve, which is shown by way of example in the right half (without reference numeral). Using this failsafe valve 8th Emergency running properties of the vibration damper can be adjusted.

In previously known embodiments (eg the not yet published German patent application 10 2014 115 577.7 ) has the valve body 32 for the rebound stage as well as for the compression stage a common effective area. In the case of the present vibration damper, deviating effective surfaces are at least partially distributed on the common valve body 32 provided for the tensile and the pressure stage.

The acted upon for the tensile and compressive effective areas are therefore each different in size. In the present case, a total of two active surfaces 45 . 46 intended; a first effective area 45 is on the valve body 32 arranged itself and is acted upon in both the compression and rebound by the pilot pressure. A second effective area 46 is on a pestle 47 arranged in one piece with the valve body 32 is trained. The second effective area 46 is arranged so that only during the pressure stage of the pressure from the first working space 11 directly on the second effective surface 46 acts. This results in the area difference of the acted upon in the respective stages active surfaces. Accordingly, the balance of power on the valve body change 32 , even if, for the tensile and compressive stage identical closing forces by the actuator 40 are set.

The pestle 47 is in a hole 43 arranged, having an access in the first working space 11 having. Thus, only in the compression stage, the second effective area 46 of the plunger 47 through the first workspace 11 prevailing working pressure. The radial bore 44 flows directly into the annular chamber 49 , The pestle 47 is through the annular chamber 49 passed.

Due to the additional loading of the valve body in the pressure stage by the first pressure prevailing in the working space, the position of the degression point in the associated pv diagram can be positioned independently for both stages. Thus a harder and for the compression stage a softer characteristic can be set for the rebound stage. For details, refer to the description of the 3a and 3b of the DE 10 2011 000 566 B3 directed.

However, the design is after 1 not satisfactorily achievable with current means. Because in the pressure stage applied in the first working space 11 applied working pressure the second effective area so strong that the valve body 32 can be moved to its upper stop position while the input port 41 blocked. Then the fluid could only through the second drain path 19 drain, which sets the Failsafe ID. This is undesirable.

In the 2 and 3 Now is an inventive development of Vibration damper after 1 described. The vibration damper after the 2 and 3 corresponds largely to the vibration damper of 1 ; in this respect, the previous description of the 1 directed. Only the deviations will be described below.

Although the valve body 32 to 2 almost identical to the valve body 32 to 1 ; the valve body 32 in 2 However, it is no longer intended if necessary, the entrance opening 41 the first drainage path 18 seal. For "switching" between the two drainage paths 18 . 19 is now also a closing element 37 intended. This closing element 37 is in this case a magnetic disk 37 and gets through the actuator 40 actuated.

2 shows the magnetic disc 37 in an open position, as the magnet 40 is active and a magnetic flux M generated; Fluid can now pass through the inlet opening 41 and the first drain path 18 flow away. The magnetic flux M flows from an anchor 51 of the valve body 32 acted upon in its closed position, via a magnetic Polrohrabschnitt 50 into the magnetic disk 37 ,

3 shows the magnetic disc 37 in a closed position when the magnetic flux M in the case of an actuator defect is eliminated. The magnetic disk 37 now covers the entrance opening 41 , The fluid flows through the second discharge path 19 from.

For transferring the magnetic disk 37 in the open position and holding the magnetic disk 37 in the open position, the magnetic force of the actuator is sufficient 40 when this is active and the position of the valve body 32 established. If this force of the actuator is omitted, for example in a faulty state, the magnetic disk becomes 37 by a return spring 48 acted upon in the closed position. Radial inside points the magnetic disk 37 a hole 54 on, by the largely a pressure equalization between the second flow path 19 and the back of the disc 37 can be generated. This causes the disc 37 by the pressure difference between the two drainage paths 18 . 19 is acted upon in its closed position.

In this embodiment, it is necessary that the actuator 40 with a certain base load (for example, current load of at least 0.4A) is applied to the closing element (here the magnetic disc 37 ) in its open position. At this base load, however, would the valve body 32 always be acted upon in its closed position. The vibration damper could not be operated in the soft detection so. The feather 30 now sets a counterforce for the base load of the actuator 40 ready, so even during the base load of the valve body 32 (except for the supply of fluid from the channel 9 ) is in the equilibrium of forces and thus a soft detection of the vibration damper is adjustable.

In the 4 and 5 Another vibration damper is shown, the largely the vibration damper after 2 and 3 corresponds; in this respect, only the differences are discussed below.

The magnetic pole tube section 50 from the previously described embodiment ( 2 and 3 ) is missing in this embodiment. The magnetic flux M Now go from the anchor 51 directly on the magnetic disk 37 over, since these are immediately adjacent to the anchor 51 is arranged, wherein a small air gap may be arranged therebetween. For this purpose, the magnetic disk 37 a sleeve extension 52 at least partially radially within the armature 51 is arranged. Further, it can be on two separate return springs 30 . 48 ( 2 and 3 ) are waived. For now a common return spring is sufficient 53 for returning both the valve body 32 and the magnetic disk 37 ; this common return spring 53 is between the anchor 51 and the magnetic disk 37 clamped. Consequently, there are savings in the number of components compared to the aforementioned embodiment.

In 5 eliminates the magnetic flux. The feather 53 impinges on the magnetic disk 37 in its closed position.

LIST OF REFERENCE NUMBERS

1

vibration

2

piston

3

piston rod

6

dimensionally stable, movable cover

7

drain valve

8th

Failsafeventil

9

Connecting passage between the two pilot chambers

10

cylinder tube

11

first (piston rod far) workspace

12

first fluid passage

13

first valve assembly

14

first valve disk

15

first valve seat

16

first pilot chamber

17

Fluid passage between the second working space 21 and first pilot chamber 16

18

first flow path

19

second flow path

20

one-way

21

second (piston rod side) working space

22

second fluid passage

23

second valve assembly

24

second valve disc

25

second valve seat

26

second pilot chamber

27

Fluid passage between first working space 11 and second pilot chamber 26

28

ring seal

29

bypass channel

30

Return spring

31

pilot valve

32

valve body

33

valve seat

34

second drainage passage to the second working space

35

Tang / turquoise for new assignment of reference numerals

36

one-way

37

magnetic disc

38

first drainage passage to the first working space

39

one-way

40

magnetic actuator

41

Entrance opening of the first drainage path

42

fastening pins

43

axial connection bore between first working chamber and annular chamber

44

radial bore

45

first effective area

46

second effective area

47

tappet

48

Return spring

49

annular chamber

50

magnetic polka tube section

51

anchor

52

Sleeve extension

53

common return spring

54

drilling

R1

first actuation direction

R2

second direction of actuation

A

Cylinder tube axis

p

backpressure

M

magnetic flux

Claims (10)

Controllable vibration damper (1), in particular for a motor vehicle chassis, comprising a cylinder tube (10) having a hydraulic fluid received therein sealed, a piston (2) which is axially movable within the cylinder tube (10) along a cylinder tube axis (A) and the cylinder tube (10) divided into two working spaces (11, 21), a piston rod (3) which is aligned parallel to the cylinder tube axis (A) and connected to the piston (2), wherein the piston (2) at least two fluid passages (12 , 22), by which the one working chamber (11, 21) is connected to the other working space (21, 11), wherein a first valve assembly (13) for damping the piston movement in a first actuating direction (R1) on a first fluid passage ( 12) is arranged and wherein a second valve assembly (23) for damping the piston movement in a second actuating direction (R2) on a second fluid passage (22) is arranged, each V valve assembly (13, 23) has at least one valve disc (14, 24) which is seated in a closed valve position on a valve seat (15, 25) and which is at least partially spaced from the valve seat (15, 25) in an open valve position, wherein each valve assembly (13, 23) comprises a pilot chamber (16, 26), wherein by pressurizing the pilot chamber (16, 26) the valve disc (14, 24) is biased into the closed valve position, the pressure in the respective pilot chambers (16 , 26) is adjustable by at least one pilot valve (31), wherein the pilot valve (31) comprises a valve body (32) which is movable in a defined manner between a closed position and an open position, whereby a flow cross-section between the pilot chambers (16, 26) and the work spaces (21, 11) is selectively adjustable, wherein the valve body (32) drain side connect a first discharge path (18) and a second discharge path (19) n, wherein the first flow path (18) is closed when an actuator (40) for controlling the position of the valve body (32) is inactive, characterized in that for closing the first drain path (18) is provided separately to the valve body (32) formed closing element (37). Vibration damper (1) according to the preceding claim, characterized in that the valve body (32) at least two active surfaces (45, 46) are assigned, which in turn pressurize the valve body (32) in its open valve position when pressurized, the sum of the during the Piston movement in one of the two operating directions, in particular the second actuating direction (R2), pressurized active surfaces (45) is less than the sum of the active during the piston movement in the other of the two actuating directions, in particular the first actuating direction (R1), pressurized active surfaces (45, 46 ). Vibration damper (1) according to one of the preceding claims, characterized in that the pilot valve (31) comprises exactly one valve body (32) for adjusting the pilot pressure in both pilot chambers (16, 26) and its position by means of an actuator (40) during operation is targeted. Vibration damper (1) according to one of the preceding claims, characterized in that the closing element (37) between a closed position in which it closes an inlet opening (41) of the first drain path (18), and an open position in which it the inlet opening (41) releases, is specifically displaced. Vibration damper (1) according to one of the preceding claims, characterized in that in the case of the inactive actuator (40), the closing element (37) can be acted upon by the present in the second flow path (19) pressure in its closed position. Vibration damper (1) according to one of the preceding claims, characterized in that the closing element (37) is magnetically controllable. Vibration damper (1) according to the preceding claim, characterized in that the closing element (37) is arranged in the magnetic flux (M) immediately adjacent to a magnetic element (51), in particular an armature, which upon magnetic application of the valve body (32) acted in its closed position. Vibration damper (1) according to one of the preceding claims, characterized in that a common return element (53) for returning the valve element (32) and for returning the closing element (37) is provided. Vibration damper (1) according to one of the preceding claims, characterized in that an actuator (40) is provided for loading the closing element (37) in the open position, which is also provided for adjusting the position of the valve body (32). Vibration damper (1) according to one of the preceding claims, characterized in that, in particular in the first flow path (18) or the first discharge path (18) downstream, the valve body (32) is associated with the drain side a drain valve (7) through which the drain side on the valve body (32) acting dynamic pressure (p) can be built up.

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